Due to the growing need to reduce carbon dioxide emissions of internal combustion engines, engines that are capable of using renewable fuels are becoming more and more attractive. Methanol (CH3OH) is an example of biofuel having a lot of potential for use as fuel of large piston engines in ships and at power plants. The use of methanol has many benefits. Since methanol is liquid at normal operating temperatures, it is easier to store than gaseous fuels. It can also be used in many engines with relatively small modifications to the engine design. In many cases, the engine can be operated on both methanol and fossil fuels, which increases flexibility. However, the use of methanol also has some drawbacks. Methanol has lower flashpoint than most other fuels that are used in large piston engines and is thus highly flammable. Methanol fires are also difficult to detect. In addition, methanol is poisonous and lethal in relatively small amounts. Therefore, when handling and using methanol, precautions are needed for preventing fires and for protecting the operators of the engine.
Risks related to the storing of methanol can be reduced by utilizing so called tank blanketing. The term refers to a process of introducing inert gas, such as nitrogen, into the vapor space of a methanol tank. When the air in the tank is replaced with inert gas, the oxygen concentration in the tank can be lowered to a level, which prevents ignition of the methanol. Also evaporation of methanol can be reduced. Tank blanketing is an effective means for protecting a fuel tank, but it does not remove the hazards relating to leakages from other parts of a fuel system.